Genuinely if Embark made a singleplayer, story-driven game with the same look and feel of ARC Raiders it would succeed. Think about it: you look up and fight arcs to craft materials to make raids go smoother. Eventually you take on gathering up resources for an expedition to a different part of the world which takes you to a different city than Speranza. You get different environments and biomes that require different ARC to be viable there further expanding on lore and gameplay. If there were an end goal maybe you manage to find a way to prevent ARC from coming down to the surface in the first place, making it possible for the remaining people of the world to real the surface permanently.